Dietary cholesterol has been known as a dominant factor in the genesis of atherosclerosis since 1908. The evidence for the role of dietary cholesterol is based upon animal experiments, the chemistry of atherosclerotic plaques, worldwide epidemiology, and human feeding studies. All lines of evidence converge to indicate that dietary cholesterol is a major factor in promoting the growth of the atherosclerotic plaque by increasing its cholesterol content. Confusion about dietary cholesterol has arisen because amounts above a certain quantity (the ceiling) do not elevate plasma cholesterol and low-density lipoprotein cholesterol. The therapeutic threshold for dietary cholesterol is below 100 mg/d.